Success! SpaceX Dragon cargo ship nails another mission.

In this frame from NASA TV, the SpaceX Dragon capsule arrives at the International Space Station bearing supplies on Wednesday, July 20, 2016. The shipment includes a docking port needed for future rocket ships.

The International Space Station got a special two-ton delivery earlier today, as SpaceX's Dragon spacecraft capsule arrived at the station as it hung in orbit some 250 miles above the Great Lakes.

The cargo included a space station docking port, needed for future rocket ships coming to the station. The port's arrival at the ISS has been a long time coming – a year ago similar docking rings were destroyed in a SpaceX launch accident.

Scientists aboard the station eagerly received the latest shipment, using a robot arm.

Mission Control replied, "This event is an important step on the journey of the International Space Station mission. Now let's get this vehicle berthed so we can get to work."

In addition to the docking port, the cargo included a DNA sequencer, which will be used by NASA astronaut Kate Rubins as she looks for viruses in space.

SpaceX's Dragon has a long history with the International Space Station. In 2012, it became the first commercial spacecraft in history to deliver cargo to the station and complete a return trip to Earth. Today's mission is just the latest in a string of regular deliveries that the craft has made, one of which even included Christmas gifts from home for the astronauts aboard.

Before SpaceX's entry into this role, these missions of delivering and returning cargo were undertaken by government spacecrafts.

SpaceX is one of several of names that are part of a growing trend in space innovation, where private sector companies who develop space crafts contract with the government for a variety of tasks. Other groups include Blue Origin and Virgin Galactic, who contract with NASA for suborbital flights.

The unmanned deliveries to the space station are only one notch that SpaceX hopes to put in the Dragon's belt. According to their website, the company is currently working on making the Dragon ready to fly crew, with approval from NASA. Boeing is working on a similar project, the Starliner, which would be a capsule for astronauts.